Millennial-scale Arctic sea ice reconstructions do not corroborate alarmist claims of unprecedented sea ice losses in modern times.
Using sea ice biomarker proxy (IP25), scientists (Kolling et al., 2023) have determined that the sea ice extent in the Labrador Sea was nearly absent throughout the year (close to 0.0 μg/gTOC) for much of the last 9,000 years. The sea ice was lowest (~0.1 μg/gTOC) 9,300 to 8,900 years ago, and low (~0.4 μg/gTOC) from 7,500 to 4,000 years ago.
In contrast, modern sea ice now lasts 23 weeks per year and is the highest in the last 9,000+ years (~1.6 μg/gTOC).
Image Source: Kolling et al., 2023
The lack of a trend in sea ice loss across the Labrador Sea is consistent with observations that show the region has not warmed in the last 70 years (Yashayaev and Loder, 2017).
Image Source: Yashayaev and Loder, 2017
Other scientists (Wu et al., 2020) determined that from about 14,000 to 8,000 years ago, when CO2 lingered near 250 ppm, the Beaufort Sea (Arctic) was “nearly ice free throughout the year” (<0.2 PIP25) and ~4°C warmer than today in winter.
With modern (1988-2007) CO2 at ~400 ppm, this region is 70-100% ice-covered (>0.8 PIP25) for 10 to 11 months per year.
Image Source: Wu et al., 2020
Svalbard sea ice has expanded to its highest extent of the Holocene (11,700 years ago to present) during the last 500 to 700 years (Allaart et al., 2020).
The Holocene’s sea ice maximum just developed during modern times, as the authors note there has been an “increase in IP25 concentrations after c. 0.7±0.2 cal. ka BP, with a maximum in the modern sediments.”
Image Source: Allaart et al., 2020
A study site northeast of Svalbard, scientists (Brice et al., 2020) find today’s sea surface temperatures of “<0°C” are at least 4°C colder than they were just a few thousand years ago, when the Arctic was sea ice free for all but “a couple of months” every year.
Today’s sea ice monthly duration (~11 months per year) and summer sea surface temperatures (zero degrees Celsius) are among the highest and lowest (respectively) of the Holocene.